High-performance brake rotors for aircraft, automobiles, and other vehicles are sometimes manufactured by forming brake rotor preforms (also sometimes referred to herein as “preforms”) from multiple layers of annular-shaped segments of woven and/or non-woven material having fibers extending in chordal, radial, or both directions. The segments are needled together in the vertical direction with a needling machine in an attempt to form a unitary structure from the layers of annular-shaped segments. Typically, the preforms are then carbonized by heating to a temperature of greater than 1,200 degrees Celsius in a non-reactive atmosphere. Subsequently, a carbon matrix is added to the preforms using a carbon vapor deposition (CVD) or resin infiltration process to make a carbon-carbon composite friction material. After heat treating in a furnace, the preforms are then machined to produce brake rotors.
The CVD process is capital-intensive and to add sufficient matrix material, the preforms must usually be subjected to multiple cycles of CVD processing that are lengthy in time. As compared to CVD, resin infiltration uses a relatively inexpensive source of carbon to add matrix material to preforms. Typically, the resin infiltration process provides for faster addition of carbon matrix material to preforms. However, resin infiltration of preforms requires the use of high pressure to force pitch into and within the preforms and, sometimes, the preforms blow apart or become delaminated during this process. In either process, matrix carbon is more easily and rapidly added with a lower density preform. And, the matrix carbon, whether formed by CVD or resin infiltration, is of lower cost than carbon fiber.
There is, therefore, a need in the industry for a brake rotor preform having a lower density that may be used in connection with a variety of processes to produce carbonized brake rotor preforms, and that resolves these and other problems, difficulties, and shortcomings associated with the manufacture of carbonized brake rotor preforms.